Plastic block bag with a valve

ABSTRACT

A block bag with a filling valve, whereby second heat seals are used for connecting the flap constituting the valve with bottom flap parts, whereby the shortest distance between the second heat seals is equal or more than the distance between the side edges formed by the inwards folded bottom parts.

D United States Patent 11 1 1111 3,896,708 De Vries July 29, 1975 PLASTIC BLOCK BAG WITH A VALVE [56] References Cited [75] Inventor: Jan Roelof Jochum Hendrik De UNITED STATES PATENTS Vries, Hardenberg, Netherlands 3,043,199 7/1962 Niemeyer 93/8 VB [73] Assignee: Industriele Onderneming Wavin 3l9580l g g g ii' at '5 VB N'v Zwolle Netherlands 3,237,534 /1 6 Issuer. VB X 3,272,093 9/1966 Brockmuller 93/8 VB [22] Fil d; O t, 23, 1973 3,657,975 4/1972 Feldkamper et al. 93/8 VB 3,688,650 9/1972 De Vries 93/8 VB X [21] Appl. No.: 408,306

Related U.S. Application Data i f ry ExamiaerRoy Lake [62] Division of Ser. No. 153,474, June 18, 1971. Pat. No. Examme [ames 3,785,541 Attorney, Agent, or Firm-Edmund M. .lasklewlcz [30] Foreign Application Priority Data [57] ABSTRACT June 17, 1970 Netherlands 7008908 A block b i h a filling valve, whereby second heat Jan. 10, 1971 Netherlands 7101739 seals are used for connecting the flap constituting the Mar. 5, 1971 Netherlands 7103404 valve with bottom flap parts, whereby the shortest tance between the second heat seals is equal or more [52] U.S. Cl 93/35 R; 93/8 VB h the distance between the side edges formed by [51] Int. Cl B311) 1/84 h inwards folded bottom parts [58] Field of Search 93/35 R, 35 SB, 8 VB, 8 R

b 17a 28216 15a 4 Claims, 5 Drawing Figures PATENTEI] JUL 2 9 I875 EET PLASTIC BLOCK BAG WITH A VALVE This application is a division of Ser. No. 153,474, filed June 18, 1971, now U.S. Pat. No. 3,785,547.

The invention relates to a plastic block bag with a filling valve obtained from a tubular foil part by making from one end thereof at least one longitudinal incision whilst forming a first, a valve flap constituting, corner flap between the longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto, folding outwards the first corner flap and folding the bottom flap parts, situated beside the longitudinal incision, about a folding line extending in the area next to the end points of the incisions, whilst forming a bottom square with a first corner flap and a second corner flap, folding inwards the bottom flaps about a transverse folding line and forming first sealed joints for connecting the bottom flap parts and forming second sealed joints connecting the first corner flap part, constituting the valve flap, with the bottom flaps, the arrange-ment being such that the folding edges of the bottom flap parts extend, when the bottom is flat, perpendicularly to the longitudinal edges of the tubular foil in the area between the initial folding line and a line extending, through the end point of the incision, almost perpendicularly to the longitudinal edges of the tubular foil.

Such a method has the drawback that the valve flap of the block bag does not close quite satisfactorily in the filled condition of the bag. This is caused by the fact that when the bag is filled the valve flap cannot be stretched and no faultless scaling is ensured.

It is an object of the invention to obviate these difficulties by providing such a plastic block bag that the valve flap, when the bag is filled, is stretched and as a consequence a faultless sealing is ensured.

This object is attained according to the invention in that the shortest distance between the second longitudinal sealed joints is at least equal to the distance between the lateral edges formed by the inwards folded bottom flap parts.

The invention relates also to a method for manufacturing a plastic block bag with filling valve obtained from a tubular foil by making from one end of the tubular foil at least one longitudinal incision whilst forming a first corner flap, also constituting the valve flap, between the longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto, folding outwards the first corner flap and the bottom flap parts situated beside the longitudinal incision about a folding line extending in the tubular foil part next to the end point of the incision, whilst forming a bottom square with a first corner flap and a second corner flap, folding inwards the bottom flaps about a cross folding line whilst inserting a partition means which at least partially has a width corresponding with the distance between the eventual folding edges, and forming first sealed joints for connecting the bottom flap parts and second sealed joints connecting the first angular flap part. situated under the bottom flap parts and constituting the valve flap, with the bottom flap parts.

In this known method the partition member consists of a flat plate-shaped body of uniform width and thickness, the member being provided with sealing members. The stamp applied on the outer side to the turned over bottom valve parts carries likewise sealing members which, when the stamp and the partition member are lying on each other, are situated opposite one the other, so that from both sides a sealing effect is applied. In this way it is possible to manufacture extraordinary good bags from tubular foil with a rather great thickness of wall, especially valve bags, which are used for packing fertilizer and like substances.

In order to attain the object of the invention the partition member provided under the bottom valves has, at least over the effective length of the second sealed joints to be formed connecting the valve flap with the bottom flaps, a width smaller than that of the part which is under the bottom flaps and which is next to the end of the valve flap, on the other hand the height of the partition member is selected in such a way that the total circumference of a cross section through the partition member is always constant, while the second sealed joints are provided in such a way that in the finished bottom their shortest distance is at least equal to the distance between the edges to be turned over in the part next to the valve flap. After the partition member has been removed the valve flap part is stretched under the bottom part formed by the bottom flaps and when forces are exerted on the valve on the inner side of the bag this valve part will tend to contact the bottom formed by the bottom flap parts.

The invention relates likewise to a device for performing the method, comprising at least one partition member and a sealing stamp cooperating therewith, the partition member and/or the sealing stamp having first and second sealing members situated opposite each other, characterized in that the partition member over a raised part has a smaller width, while on the other hand the height and shape in the area of this smaller width is selected in such a way that the circumference of a cross section of the partition member is always equal to the circumference of the cross section in the wider part of the partition member, while the second sealing members for sealing together the valve flap and the tubular foil body on the partition member are provided in such a way that their smallest distance measured over the circumference of the partition member is at least equal to the half circumference of the parti? tion member in its widest area.

The invention is hereinafter clarified with reference to the drawing in which an embodiment is represented.

In the drawing:

FIG. 1 shows a flattened tubular foil part used for manufacturing a plastic bag;

FIG. 2 shows to a reduced scale a tubular foil part according to FIG. I in a folded condition;

FIG. 3 represents abag with finished bottom; and

FIG. 4 is a perspective view of a partition member applied in order to obtain a bottom of a plastic bag according to FIG. 3;

FIG. 5 is a perspective view of a block bag provided with a valve of a more flexible foil than the foil of the bag.

FIG. 1 represents a flattened tubular foil part 1 with longitudinal edges 2 and 3 and a front and back wall 4, 5 respectively. From one end of the tubular foil 1 a first longitudinal incision 6 is made whilst forming a first inner corner flap 7, also constituting the valve flap, between the longitudinal incision 6 and the longitudinal edge 2 of the tubular foil situated closest thereto. On the other side of the longitudinal incision 6 are the bottom flaps 8 and 8'. These bottom flaps have a length shorter than the first comer flap 7, 7.

In the tubular foil part 1 a second longitudinal incision 9 is provided, which extends parallelly to the longitudinal edge 3 of the foil, whereby a second corner flap is formed. This second corner flap 10 has a length shorter than that of the bottom flaps 8 and 8'. The first longitudinal incision 6 and the second longitudinal incision 9 end in end points 11, 11 and l2, 12. These end points 11, 11 and 12, 12' of the incisions can be con- 1 nected by a line extending perpendicularly to the longitudinal edges 2 and 3 of the tubular foil. The part of the tubular foil which comprises the first corner flap 7, 7 the bottom flaps 8, 8' and the second corner flap l0, 10 is unfolded about a folding line 13 extending in the area next to the end points 11, 11', 12, 12 of the incisions. In this way a bottom square with a first corner flap 7 and a second corner flap 10 is formed. The bottom flaps 8, 8 are subsequently inwards folded whilst forming folding edges 14a, 14b which extend perpendicularly to the longitudinal foil edges 2 and 3. These folding edges of the bottom flap parts extend also in the area between the initial folding line 13 and a line extending through the end points ll, 11' of the incision, which line is perpendicular to the longitudinal edges 2 and 3 of the tubular foil.

The parts folded over each other of the bottom flaps 8, 8 are interconnected by first sealed joints a, 15b, while the second corner flap 10 is connected by means of sealed joints 16a, 16b, 16c with the bottom flaps 8, 8.

Also the sealed joints 17a, 17b are formed for connecting the valve flap part 18, formed by the bottom flap 7, with the bottom flaps 8, 8. The sealed joints 17a, 17b formed in such a way that the distance between these sealed joints is at least equal to the distance between the side edges 14a, 14b formed by the inwards folded bottom flap parts.

When a flat partition member is used within the bag on forming the first sealed joints 15a, 15b and the sealed joints 16a, 16b and 160 and the second sealed joints 17a, 17b it is because of the thickness of the partition member almost impossible to form the sealed joints on or in the vicinity of the final folding edges 14a, 14b of the bottom flaps formed on folding the latter. This is possible indeed by using a partition member as represented 'in FIG. 4. This partition member is provided with second sealing members 19 for forming the second sealed joints 17a, 17b and the first sealing members 20 for forming the first sealed joints 15a, 15b for connecting the bottom flaps.

As is visible the width b of the partition member increases in the direction of the end carrying a triangular end part; the greatest width being about at the location whereat the part 21a of the partition member is connected with the triangular part 21b of the partition member. As is visible the beginning of the part 21a of the partition member is raised. The circumference of a cross section at an arbitrary point of the partition member is, however, always such that the circumference of this cross section is almost equal to the circumference of the cross section of the part 21a of the partition member in its widest part, situated between the prints 22a and 22b.

In order to ensure that after removal of the partition member the second sealed joints formed 17a, 17b come to lie practically exactly on the eventually formed folding edges of the corner flaps 8, 8 it is necessary that the distance of the two second sealing members 19 measured on the surface of the partition member is substantially at least equal to the distance between the end points 22a and 22b of the first partition member part 21a, which endpoints 22a, 22b are situated on the connecting line between a first part 21a and a second part 21b of the partition member.

After folding the bottom flaps and associated corner flap parts a sealing stamp (not shown) adapted to the partition member is applied thereto, this sealing stamp likewise carrying first and second sealing members, which in the effective position lie opposite the first sealing members 20 and second sealing members 19, and the sealing members 23a, 23b and 230 for forming the sealed joints 16a, 16b and 160.

It is obvious that due to the application of such a partition member the sealed joint can be easily formed in the part that will constitute the eventual folding edges of the bottom flaps.

It has been found that in this way a securing of the valve is obtained which ensures that the valve flap 18, when the bag has been filled, on account of the contents of the bag will come to lie against the bottom formed by the bottom flaps 8, 8'. In this way a faultless closure of the bags is obtained. It has also been found that due to the simultaneous effect of sealing heat from the outer side and from the inner side on the foil parts to be connected an extraordinary firm sealed jointis obtained, while on the other hand the way in which the valve flap 18 is secured ensures an absolutely dependable sealing.

In particular cases it is advisable to subject the free edge 24 of the bottom flaps 8, 8', which are sealed to each other, to an additional thermal treatment, e.g. when the sealed joints are formed, whereby a beaded edge is obtained which ensures an easier introduction of the nozzles of the filling machines into such valve bags. Moreover it is possible to subject the triangular part 25a, indicated in FIG. 3, at the folding line 14 to an additional sealing treatment which contributes to a proper introduction of the nozzle into the plastic bag. It depends from case to case, however, whether this measure will be used or not. An analogous sealing together of the parts in the triangular part 25a will then also be effected in a triangular part 25b.

According to a preferred embodiment free ends of the sealed joints are in the shape of rounded off seals. Such a rounded off free end 28 at the end of the sealed joints 17a and 17b is shown in the FIG. 5. The rounded off free ends 28 are situated at the end edge 26 of the valve flap 7, 7. In order to obtain the rounded off free ends the sealing members 19 are provided with rounded off ends 27. Similar rounded off ends 29 can be obtained by means of sealing members 23a. In this way any tearing of the bag at the seal ends is prevented.

Still another embodiment is shown in FIG. 5, wherein the first comer flap 7, 7' constituting the valve of the bag is connected with an auxiliary flap 31 of relatively flexible thin thermoplastic material. This fexible material is thinner than corner flap 7, 7. The connection is obtained by placing said thin foil 31 under the first corner flap 7, 7', the flap 31 being positioned such that the short edges 32 of the flap 31 coincide nearly with the free edges 33 of the flap 31. After folding of the bottom flaps 8, 8' inwards along the folding edges 14 and 14', the flap 31 is connected with the corner flap 7, 7' by means of heat seals 36. These heat seals prevent displacement and tearing off of the flap 3].

Furthermore seals 37 are provided in the region parallel to the folding edges 14, 14' in order to connect the longitudinal edges 32 with the bottom flaps 8, 8', The provision of the thinner flap 31 (eg having half of the thickness of the foil material constituting the first corner flap 7, 7') ensures a reliable closure of the valve which is not always the case with first corner flaps 7, 7'. It is recommended to apply rounded seal ends in the region of inner end edge 26 of flap 31 and preferably also in the region of inner end edge 38 of first corner flap 7, 7

The edges 35 from the entrance of the valve.

It will be obvious that the flap 31 is connected with the bag during manufacture of the bottom seals of the bag.

I claim:

1. A method of manufacturing a plastic block bag with a filling valve from a tubular foil comprising the steps of making from one end of the tubular foil two longitudinal incisions one on each side of'the longitudinal center line of the tubular foil to form a first corner flap between one longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto, a second corner flap between the other longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto and a pair of bottom flaps between the two longitudinal incisions; folding outwardly the first corner flap and the second corner flap together with the bottom flaps along folding lines extending at angles toward the one end of the foil from the longitudinal edges to the ends of the longitudinal incisions to form a bottom square with the first corner flap and the second corner flap; folding inwardly the bottom flaps along lines transverse to the longitudinal center line of the tubular foil such that the bottom flaps are in overlapping relationship; inserting a removable partition member between the remaining portion of the first corner flap and the inwardly folded bottom flaps and between the remaining portion of the second corner flap and the underlying portions of the tubular foil; forming first seals to connect the edges of the bottom flaps to each other, forming second seals immediately underneath the bottom flaps to connect the first corner flap with the bottom flaps to form a valve flap; the width of that portion of the removable partition member at least along the effective length of the second seals being smaller than the width of the distance between the bottom flap folding lines of the finished bag with a flattened bottom; and removing the partition member from under the bottom flaps after the seals have been formed.

2. A method as claimed in claim 1 and applying heat to either side of the foil parts to be connected to form the seals.

3. A method as claimed in claim 1 and providing the first corner flap with an auxiliary valve flap of a material having a thickness less than the thickness of the material of the tubular foil.

4. A method of manufacturing a plastic block bag with a filling valve from a tubular foil comprising the steps of making from one end of the tubular foil two longitudinal incisions one on each side of the longitudinal center line of the tubular foil to form a first corner flap between one longitudinal incision and the longitudinal edge of tubular foil situated closest thereto, a second corner flap between the other longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto and a pair of bottom flaps between the two longitudinal incisions; folding outwardly the first corner flap and the second corner flap together with the bottom flaps along folding lines extending at angles toward the one end of the foil from the longitudinal edges to the ends of the longitudinal incisions to form a bottom square with the first corner flap and the second corner flap; folding inwardly the bottom flaps along lines transverse to thelongitudinal center line of the tubular foil such that the bottom flaps are in overlapping relationship; inserting a removable partition member between the remaining portion of the first corner flap and the inwardly folded bottom flaps and between the remaining portion of the second corner flap and the underlying portions of the tubular foil; forming first seals to connect the edges of the bottom flaps to each other, forming second seals immediately underneath the bottom flaps to connect the first corner flap with the bottom flaps to form a valve flap; the width of the portion of the removable partition member at least along the effective length of the second seals being smaller than the width of the partition member immediately under the bottom flaps adjacent to the end of the valve flap, the height of the partition member being such that the total circumference of a cross section of the partition member is constant, the shortest distance between the second seals measured over the top of the removable partition member is at least equal to the distance between the folding edges of the bottom flaps of the finished bag with a flattened bottom. 

1. A method of manufacturing a plastic block bag with a filling valve from a tubular foil comprising the steps of making from one end of the tubular foil two longitudinal incisions one on each side of the longitudinal center line of the tubular foil to form a first corner flap between one longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto, a second corner flap between the other longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto and a pair of bottom flaps between the two longitudinal incisions; folding outwardly the first corner flap and the second corner flap together with the bottom flaps along folding lines extending at angles toward the one end of the foil from the longitudinal edges to the ends of the longitudinal incisions to form a bottom square with the first corner flap and the second corner flap; folding inwardly the bottom flaps along lines transverse to the longitudinal center line of the tubular foil such that the bottom flaps are in overlapping relationship; inserting a removable partition member between the remaining portion of the first corner flap and the inwardly folded bottom flaps and between the remaining portion of the second corner flap and the underlying portions of the tubular foil; forming first seals to connect the edges of the bottom flaps to each other, forming second seals immediately underneath the bottom flaps to connect the first corner flap with the bottom flaps to form a valve flap; the width of that portion of the removable partition member at least along the effective length of the second seals being smaller than the width of the distance between the bottom flap folding lines of the finished bag with a flattened bottom; and removing the partition member from under the bottom flaps after the seals have been formed.
 2. A method as claimed in claim 1 and applying heat to either side of the foil parts to be connected to form the seals.
 3. A method as claimed in claim 1 and providing the first corner flap with an auxiliary valve flap of a material having a thickness less than the thickness of the material of the tubular foil.
 4. A method of manufacturing a plastic block bag with a filling valve from a tubular foil comprising the steps of making from one end of the tubular foil two longitudinal incisions one on each side of the longitudinal center line of the tubular foil to form a first corner flap between one longitudinal incision and the longitudinal edge of tubular foil situated closest thereto, a second corner flap between the other longitudinal incision and the longitudinal edge of the tubular foil situated closest thereto and a pair of bottom flaps between the two longitudinal incisions; folding outwardly the first corner flap and the second corner flap together with the bottom flaps along folding lines extending at angles toward the one end of the foil from the longitudinal edges to the ends of the longitudinal incisions to form a bottom square with the first corner flap and the second corner flap; folding inwardly the bottom flaps along lines transverse to the longitudinal center line of the tubular foil such that the bottom flaps are in overlapping relationship; inserting a removable partition member between the remaining portion of the first corner flap and the inwardly folded bottom flaps and between the remaining portion of the second corner flap and the underlying portions of the tubular foil; forming first seals to connect the edges of the bottom flaps to each other, forming second seals immediately underneath the bottom flaps to connect the first corner flap with the bottom flaps to form a valve flap; the width of the portion of the removable partition member at least along the effective length of the second seals being smaller than the width of the partition member immediately under the bottom flaps adjacent to the end of the valve flap, the height of the partition member being such that the total circumference of a cross section of the partition member is constant, the shortest distance between the second seals measured over the top of the removable partition member is at least equal to the distance between the folding edges of the bottom flaps of the finished bag with a flattened bottom. 